Because of a good profile of properties including heat resistance, low-temperature performance, chemical resistance, solvent resistance and oil resistance, heat-curable fluoropolyether base rubber compositions are used in a wide variety of applications, typically in the automotive industry, as disclosed in JP-A 2001-192546, JP-A 2000-248166, and JP-A 2002-020615. Since heat is necessary for these compositions to cure, a problem arises if it is desired to apply the compositions to large-size parts which are too large to place in a heating oven or heat-sensitive parts.
In contrast, RT curable fluoropolyether base rubber compositions of the condensation cure type dispense with heat in forming cured products, and the cured products have improved properties including heat resistance, low-temperature performance, chemical resistance, solvent resistance and oil resistance as disclosed in JP-A H09-077944, JP-A H09-137027, JP-A H09-263639, and JP-A H09-263640. These compositions are expected to find a variety of applications. However, the prior art well-known RT curable fluoropolyether base rubber compositions of the alcohol-removal condensation cure type have some problems. The synthesis route of the base polymer is complex. Since hydrolyzable groups are at both ends of the polymer chain, hydrolysis gradually proceeds with the lapse of time and hence, the base polymer builds up its viscosity. That is, the base polymer has poor storage stability.
JP-A H09-151171 describes an organic fluorine compound having amino groups at both ends which has the advantages of relatively easy synthesis and good storage stability. Although a cured product may be obtained by reacting an organic fluorine compound having amino groups at both ends with a compound having acid fluoride group ((C═O)F) or ester groups at both ends as disclosed therein, the curing rate is as slow as practically unacceptable. There is a desire to have a composition which is effectively curable (or has an appropriate curing rate) at room temperature and offers a cured product having improved properties such as heat resistance, low-temperature performance, chemical resistance, solvent resistance and oil resistance.